(a) Field of the Invention
The present invention relates to a plasma display panel (PDP). More particularly, the present invention relates to an AC-PDP that forms discharge cells by including address electrodes on a rear substrate, and sustain electrodes comprised of scan electrodes and common electrodes on a front substrate.
(b) Description of the Related Art
A PDP is a display device that uses vacuum ultraviolet rays generated by gas discharge in discharge cells to excite phosphors, thereby realizing the display of images. With its ability to realize high-resolution images, the PDP is emerging as one of the most popular flat panel display configurations used for wall-mounted televisions and other similar large-screen applications.
The different types of PDPs include the AC-PDP, DC-PDP, and the hybrid PDP, depending on the voltage application method. The AC-PDP utilizing a triode surface discharge structure is becoming the most common configuration.
In the AC-PDP with a triode surface discharge structure, address electrodes, barrier ribs, and phosphor layers are formed on a rear substrate. Sustain electrodes comprised of scan electrodes and common electrodes are formed on a front substrate. A dielectric layer is formed covering the address electrodes on the rear substrate, and another dielectric layer is formed covering the sustain electrodes on the front substrate. Discharge cells are formed by the intersection of the address electrodes with the sustain electrodes, and discharge gas (typically an Ne—Xe compound gas) is filled in the discharge cells.
Using the above structure, an address voltage Va is applied between an address electrode and a scan electrode to select a discharge cell where illumination is to take place through address discharge. Next, if a sustain voltage Vs is applied between the common electrode and the scan electrode of all discharge cells, plasma discharge occurs in the selected discharge cells. Vacuum ultraviolet rays are emitted from the excited Xe atoms created during plasma discharge. The vacuum ultraviolet rays excite phosphors so that they glow (i.e., emit visible light) and thereby enable the display of predetermined color images.
In the PDP structured and operating as described above, several steps are involved between when power is input to the PDP to when visible light is emitted therefrom. However, the efficiency of energy conversion (i.e., brightness ratio relative to consumed power) in each of these steps is relatively low. The overall energy conversion efficiency of the PDP is, in fact, lower than that of the CRT. Therefore, an important objective pursued by PDP manufacturers is that of enhancing energy conversion efficiency.
In Japanese Laid-Open Patent No. 2000-285814, two problems of the AC-PDP with a triode surface discharge structure are pointed out. The first has to do with varying discharge intensities of the discharge cells. That is, depending on the position of the discharge cells along lines of the same in the direction of the sustain electrodes, the discharge intensities of the discharge cells vary. This results in a brightness over the screen of the PDP that is not uniform.
The second problem of the AC-PDP as indicated in the above-referenced application is that mis-discharge occurs between discharge cells adjacent along the direction the address electrodes are formed. This may result in poor picture quality since unintended phosphor layers are illuminated.
In an effort to overcome these problems, the above-referenced application discloses a configuration in which one scan electrode and two common electrodes are mounted corresponding to each discharge cell. Since two common electrodes are provided for every one scan electrode, a resistance value for a predetermined unit of length of each pair of the common electrodes is double a resistance value for an equal unit of length of each of the scan electrodes.
Each of the scan electrodes in this application includes a transparent electrode and a metal bus electrode to provide a suitable level of conductivity to the transparent electrodes. Similarly, each of the common electrodes includes a transparent electrode and a metal bus electrode to provide a suitable level of conductivity to the transparent electrodes. Further, barrier ribs are formed in a striped pattern parallel to the address electrodes.
However, there are significant drawbacks to such a structure disclosed in Japanese Laid-Open Patent No. 2000-285814. First of all, since the bus electrodes mounted on the scan electrodes and common electrodes are exposed in the areas of discharge, the amount of discharge current flowing through the sustain electrodes is significantly increased. This causes an increase in the amount of power consumed to thereby reduce PDP efficiency, and also acts as a hindrance to realizing uniform brightness in the discharge cells such that overall picture quality is reduced.
Another drawback to the above structure is that limitations are placed on increasing the number of pixels along the direction of the address electrodes by mounting three sustain electrodes for each discharge cell. This limits attempts at enhancing picture quality. Further, if steps are taken to obtain high picture quality using the basic configuration described above, crosstalk occurs between adjacent discharge cells.
Finally, one way in which PDP efficiency is enhanced is to increase the Xe content or the Xe—He compound gas content in the discharge gas. However, with the above electrode structure and particularly the barrier rib structure described above, such a change in the discharge gas makes address discharge and sustain discharge unstable. Therefore, only a very limited effectiveness of altering the discharge gas components is achieved.